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Former Member
Jan 11, 2011 at 02:04 PM

Bad performance due to "db file parallel write"

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Hi everyone,

I have a case where I am somewhat struck. The end users are complaining

that the performance is really bad. System data: ECC 6.0 / Oracle 10.2.0.4.

We can easily see that the wait event "db file parallel write" from the

8 DBWR processes is really high. Also the number of archived redo logs

written is much higher (20-30 per hour compared to normally 2 per hour).

When analyzing the ADDM data for the periods experiencing bad performance

I can find 5 expensive SQL statements with roughly the same tuning

benefit estimation:

6tvk271cbac3t DELETE FROM "VAPMA" WHERE "MANDT"=:A0 AND "VBELN"=:A1
6c0pw8gqhbbbf UPDATE "INDX" SET "LOEKZ"=:A0 , "SPERR"=:A1 , "AEDAT"=:A2 , ...
49rc57zc9nc3x UPDATE "USR02" SET "BCODE"=:A0 , "GLTGV"=:A1 , "GLTGB"=:A2 , ...
3cmgznkdm332x INSERT INTO "VBMOD" VALUES(:A0 ,:A1 ,:A2 ,:A3 ,:A4 )
c33yvn1gan03y INSERT INTO "ARFCSDATA" VALUES(:A0 ,:A1 ,:A2 ,:A3 ,:A4 ,:A5 ,:A6 ,:A7...

Is there any simple way of extracing the redo log sizes for these statements

from AWR data? I already checked the resource kit from note 1438410, but

couldn't find anything which would help with this specific problem.

Do I have to use Oracle LogMiner to get this information? Or is this information buried

somewhere in some DBA_HIST_.... view?

Regards,

Mark